Gasoline composition containing n-alkyltrimethyllead



atoms.

United States Patent 3,342,571 GASOLINE COMPOSITION CONTAINING n-ALKYLTRIMETHYLLEAD Maurice R. Barusch, Richmond, Wallace L. Richardson,

Lafayette, and George J. Kautsky, El Cerrito, Calif.,

assignors to Chevron Research Company, a corporation of Delaware No Drawing. Continuation of application Ser. No. 397,324, Sept. 17, 1964, which is a continuation of application Ser. No. 25,526, Apr. 29, 1960. This application June 9, 1966, Ser. No. 556,523

2 Claims. (Cl. 44-69) ABSTRACT OF THE DISCLOSURE Hydrocarbon base fuel having a clear Research octane number of at least 95 and from 20 to 60 percent by volume of aromatic hydrocarbons contains from about 0.5 to about 4 milliliters of n-alkyltrimethyllead per gallon, said n-alkyl group containing from 3 to 8 carbon rice R. Barusch, Wallace L. Richardson and George 1.

Kautsky US. application Ser. No. 25,526, filed Apr. 29, 1960, now abandoned.

This invention relates to an improved gasoline composition. More particularly, the invention is concerned with a superior new hydrocarbon fuel of the gasoline boiling range containing n-alkyltrimethyl lead in which the n-alkyl group contains from 3 to 8 carbon atoms.

Gasoline compositions of high octane number are commonly required for modern spark ignition internal combustion automobile and aircraft engines. Engines of these types in general use today are designed with high compression ratios for more efiicient operation. Since the present trend is toward engines of still higher compression ratios for increased power and improved performance, there is a constant demand for gasoline compositions of even higher octane number.

Improved methods of refining and blending gasoline base stocks, and additives such as lead tetraethyl, have been employed to-meet the demands for higher octane number.gasolinecompositions. However, it has been generally'realized .that. there is at present a limit to the improvement inoctane number thatcan be obtained by such conventional methods and additives. New gasoline base stocks with the combination of different additives are greatly needed, therefore, to avoid present limitations and provide gasoline compositions of high octane number for future use in automobile and aircraft engines.

It has now been found that a superior new gasoline composition of high octane number is provided by a hydrocarbon base fuelboiling in the gasoline boiling range to which is added n-alkyltrimethyl lead having from 3 to 8 carbon atoms in the alkyl group, in amounts suflicient to improve the octane number, preferably at least 0.5 milliliter per gallon of base fuel.

The improved gasoline compositions of the invention show unexpectedly high octane numbers compared to previously known combinations of hydrocarbon base fuels and additives. Hydrocarbon base fuels, together with the specified n-alkyltrimethyl lead compounds and mixtures thereof in accordance with the invention, have octane numbers which are substantially higher than similar base fuels employing the conventional lead tetraethyl additive in the same lead content. This is surprisreflux for about ing since it has been generally accepted heretofore that other lead compounds are distinctly less elficient than lead tetraethyl with respect to octane number improvement.

The hydrocarbon base fuel of the composition, according to the invention, is prepared by conventional refining and blending processes. It normally contains straight-chain paratfins, branched-chain paraflins, olefins, aromatics and naphthenes. Since straight-chain paraffins have a tendency to adversely afiect octane number, the content of such hydrocrabons is ordinarily low.

As already mentioned, the base fuel is a hydrocarbon fuel boiling in the gasoline boiling range. Generally described, such fuels have an ASTM (lD-86) distillation with an initial boiling point of about 100 F. and a final boiling point of about 425 F. Preferably, the unleaded base fuel has a Research octane number of at least as determined by the accepted] CRF engine test method. Also, the base fuel preferably contains at least 20% by volume of aromatic hydrocarbons. Less than 30% by volume of olefinic hydrocarbons are present in the fuel. The total parafiin and naphthene hydrocarbon content of the preferred fuel may be :as much as 80% by volume. For best overall engine performance, fuels containing in the range of 20 to 60% by volume of paralfinic and naphthenic hydrocarbons are preferred for volatility and other desirable gasoline The more preferred hydrocarbon base fuels are those which contain from 20 to 60% by volume aromatic hydrocarbons and from 0 to 30% by volume of olefinic hydrocarbons. Most preferably, a gasoline having allaround desirable characteristics has a clear octane number of at least and contains about 50 to 60% by volume of paraffin and naphthene hydrocarbons, about 30 to 40% aromatic hydrocarbons and about 5 to 15% olefinic hydrocarbons.

For practical purposes, not more than about 4 milliliters of lead compounds per gallon is ordinarily used in the compositions. If desired, other octane-improving additives may be employed in addition to the n-alkyltrimethyl lead. These include other lead compounds such as lead tetraethyl, carbonyl derivatives of iron and cyclopentadienyl derivativesof metals such as manganese or iron. Other gasoline additives, such as scavengers like ethylene chloride or bromide, oxidation inhibitors, corrosion inhibitors, surface ignition suppressants like phosphorus compounds, detergents, and the like may be present.

The following example illustrates the preparation of n-alkyltrimethyl lead compound in accordance with this characteristics.

EXAMPLE One mole of n-amyl magnesium bromide Grignard reagent in 1 liter of ethyl ether is prepared in the usual manner. To this is added 134 g. (0.465 mole) trimethyl lead chloride and the mixture is stirred and heated under 2 hours. The mixture is allowed to stand overnight. It is then added to about 300 ml. of saturated NH Cl aqueous solution. The ether layer is separated, water-washed and dried over anhydrous sodium sulfate. The ether is then distilled off and the remaining liquid product is fractionated at 4 mm. Hg pressure. The n-amyltrimethyl lead boils at 63 C. The yield is 73% of theory based on trimethyl lead chloride used.

In further illustration of the superior new gasoline composition of the invention, several compositions and tests thereon are given in the following additional examples. These tests show the improved effect of the combination of the hydrocarbon base fuel with n-alkyltrimethyl lead as compared with fuels containing other lead compounds.

The following table is a summary of the pertinent data of the examples. The type of compositions of the hydrocarbon base fuel is shown with respect to the percent by volume of the paraffins and naphthenes, olefins and combustion engines, having a clear Research octane number of at least 95, said fuel being characterized in that the hydrocarbon composition contains from 20 to 60% by volume of aromatic hydrocarbons, not more than fuel of Example 6 is 85.2, or 2.6 octane numbers worse.

We claim: 1. A hydrocarbon base fuel, boiling in the gasoline boiling range, adapted for use in spark ignition internal aromatics. The clear octane number of the base fuel is 30% by volume of olefinic hydrocarbons and not more also given. This octane number as already mentioned, than 60% by volume of parafilnic and naphthenic hydrois the accepted Research octane number which is usually carbons, said fuel containing from about 0.5 to about 4 employed in designating a given gasoline. This method ml. of n-alkyltrimethyllead per gallon, said n-alkyl group is described as Research Method D908 in ASTM Mancontaining from 3 to 8 carbon atoms, said fuel having ual of Engine Test Methods for Rating Fuels. 10 a Motor Method octane number greater than the cor- The table shows the effect on o t e pu y the responding octane number of a mixture of said hydroaddltioll 0f l'l-alkyltflmethyl lead contalnlng 3 t0 8 carbon composition containing a molar equivalent of bon atoms in the alkyl group, as compared to lead tetratetragthyuemlethyl. The octane number in this SOIIIPBIISOD is based on A hydrocarbon base fuel, boiling in the gasoline h Motor Method the Manual of boiling range, adapted for use in spark ignition internal Test Methods i E 3 9 f combustion engines, having a clear Research octane numi s f 2 g .5 3 2; ber of at least 95, said fuel being characterized in that 0 6 651m. 6 1 0 e 1 Pr the hydrocarbon composition contains from to 60% gasoline compositlon of the 1nvent1on. 4 b volume of aromatic h drocarbons 0t th In the table, the effect of n-alkyltrimethyl lead com- 20 3 b 1 f l fi d b n i an pared with lead tetraethyl, etc., is based on gasoline comh 0 g 0 0 mo g Focar ons an more positions containing an equal lead concentration. That is t an volume 0 Pf me and naphthemc hydro to Say, that about milliliters per gallon of carbons, said fuel containing from about 0.5 to about 4 trimethyl lead is compared with 3.00 milliliters per galof n'amyltnmethynead P gauon, 531d fuel havlng lon lead tetraethyl, while larger amounts of the higher 25 a Method Octane numb greater than the n-alkyl compounds are used because of the diiference l'espondlng Octane number of a mlxture of Said y in densities and molecular weights of the compounds. The Carbon COmPOSitiOII containing a molar equivalent f Improvement is the difference in the octane number tetraethyllead.

TABLE Hydrocarbon Composition Motor Octane Research Ex. No. n-Alkyl Paraffins Octane n-Alkyl Trimethyl Tetraethyl Improve- Group and Olefins, Aromatics, Unleaded Lead Lead ment Naphthenes, Percent by Percent by Percent by Volume Volume Volume M1. Gm N0. M1. Gm No.

47 20 33 94.1 2.6 4. 52 88.5 3.0 4. 94 88.3 0.2 47 20 33 94.1 2.8 4. 73 88.8 3.0 4. 94 88.3 0.5 47 20 33 94.1 3.1 4. 94 88.8 3.0 4.94 88.3 0.5 41 16 43 95.5 2.9 4. 52 38.2 3.0 4. 94 87.8 0.4 41 1e 43 05.6 2.8 4.73 88.7 3.0 4. 94 87.8 0.9 54 Trace 46 98.1 2.6 4.52 93.3 3.0 4. 94 95.2 1.1 54 Trace 98.1 2.8 4.73 95.0 3.0 4. 94 95.2 0.8 54 Trace 98.1 3.1 4. 94 95.8 3.0 4. 94 95.2 0.6

obtained with alkyltrimethyl lead less the octane number References Cited obtained w1th the equivalent amount of lead tetraethyl. UNITED STATES PATENTS The examples summarized 1n the above table show that the improved gasoline composition of the invention 1,592,954 7/ 1926 Mldgley 44-69 containing n-alkyltrimethyl lead having 3 to 8 carbon ,9 9,9 9 3/ 193(1- Alleman 44-69 atoms in the n-alkyl group is decidedly better on the 2,310,376 /19 'Smyers ct a1. 4469 basis of octane number rating than comparable gasoline 2,855,905 10/1958 Hinkamp et al 44-69 compositions of the type known heretofore. Surprisingly, 55 2,862,801 12/1958 De Witt 44--69 other alkyl lead compounds give decidedly worse octane numbers than tetraethyl lead. For example, tert.-butyl- OTHER REFERENCES trimethyl lead in the fuel of Example 4 gives an octane W 1.

agner et al.. Improved Motor Fuels Through Seleca i ggig' i g zg jggagi i;2 tive Blending, paper presented before 22nd meeting of y y y the American Petroleum Institute, Nov. 7, 1941, 19 pp.

DANIEL E. WYMAN, Primary Examiner. Y. H. SMITH, W. J. SHINE, Assistant Examiners, 

1. A HYDROCARBON BASE FUEL, BOILING IN THE GASOLINE BOILING RANGE, ADAPTED FOR USE IN SPARK IGNITION INTERNAL COMBUSTION ENGINES, HAVING A CLEAR RESEARCH OCTANE NUMBER OF AT LEAST 95, SAID FUEL BEING CHARACTERIZED IN THAT THE HYDROCARBON COMPOSITION CONTAINS FROM 20 TO 60% BY VOLUME OF AROMATIC HYDROCARBONS, NOT MORE THAN 30% BY VOLUME OF OLEFINIC HYDROCARBONS AND NOT MORE THAN 60% BY VOLUME OF PARAFFINIC AND NAPHTHENIC HYDROCARBONS, SAID FUEL CONTAINING FROM ABOUT 0.5 TO ABOUT 4 ML. OF N-ALKYLTRIMETHYLLEAD PER GALLON, SAID N-ALKYL GROUP CONTAINING FROM 3 TO 8 CARBON ATOMS, SAID FUEL HAVING A MOTOR METHOD OCTANE NUMBER GREATER THAN THE CORRESPONDING OCTANE NUMBER OF A MIXTURE OF SAID HYDROCARBON COMPOSITION CONTAINING A MOLAR EQUIVALENT OF TETRAETHYLLEAD. 